URP 中使用 HDR 输出的 Scriptable Render Pass 疑难解答

高动态范围 (HDR) 输出在应用色调映射和色彩空间转换时会更改 Scriptable Render Pass 的输入。这些更改可能导致 Scriptable Render Pass 生成不正确的结果。这意味着，当您使用HDR高动态范围
请参阅词汇表输出和在 AfterRenderingPostProcessing 注入点之后发生的 Scriptable Render Pass 时，您需要考虑 HDR 输出所做的更改。这同样适用于您希望在后期处理在图像显示在屏幕上之前，通过应用滤镜和特效来改善产品视觉效果的过程。例如，您可以使用后期处理特效来模拟物理相机和胶片属性，例如 Bloom 和景深。更多信息后期处理,后期处理,后期处理
请参阅词汇表期间或之后添加叠加层时，例如UI(用户界面) 允许用户与您的应用程序交互。Unity 目前支持三种 UI 系统。更多信息
请参阅词汇表或其他摄像机一个组件，用于创建场景中特定视点的图像。输出要么绘制到屏幕上，要么捕获为纹理。更多信息
请参阅词汇表的输出，因为您需要使用 HDR 输出产生的色域。为了使 Scriptable Render Pass 能够处理 HDR 输出所做的更改，您必须手动执行脚本中的色调映射和色彩空间转换。

但是，如果您在 BeforeRenderingPostProcessing 注入点或之前添加 Scriptable Render Pass，则无需进行任何更改以使其与 HDR 输出兼容。这是因为 Unity 会在渲染 HDR 输出之前执行 Scriptable Render Pass。

注意：当您使用摄像机堆栈在 Unity 执行色调映射之前渲染摄像机输出时，可以避免此问题。然后，Unity 将 HDR 输出处理应用于堆栈中的最后一个摄像机。要了解如何设置摄像机堆栈，请参阅摄像机堆栈。

在脚本中进行色调映射和色彩空间转换

为了使 Scriptable Render Pass 能够处理 HDR 输出对色彩空间和动态范围所做的更改，请使用 SetupHDROutput 函数将色调映射和色彩空间转换应用于 Scriptable Render Pass 所修改的材质。

打开包含您希望与 HDR 输出一起使用的 Scriptable Render Pass 的 C# 脚本。

在 Render Pass 类中添加一个名为 SetupHDROutput 的方法。

以下脚本提供了一个如何使用 SetupHDROutput 函数的示例。

class CustomFullScreenRenderPass : ScriptableRenderPass
{
    // Leave your existing Render Pass code here

    static void SetupHDROutput(ref CameraData cameraData, Material material)
    {
        // This is where most HDR related code is added
    }
}

添加一个 if 语句以检查 HDR 输出是否处于活动状态，以及摄像机是否启用了后期处理。如果任一条件不满足，请禁用 HDR 输出着色器在 GPU 上运行的程序。更多信息
请参阅词汇表关键字以减少资源使用。

static void SetupHDROutput(ref CameraData cameraData, Material material)
{
    // If post processing is enabled, color grading has already applied tone mapping
    // As a result the input here will be in the display colorspace (Rec2020, P3, etc) and in nits
    if (cameraData.isHDROutputActive && cameraData.postProcessEnabled)
    {

    }
    else
    {
        // If HDR output is disabled, disable HDR output-related keywords
        // If post processing is disabled, the final pass will do the color conversion so there is
        // no need to account for HDR Output
        material.DisableKeyword(HDROutputUtils.ShaderKeywords.HDR_INPUT);
    }
}

创建变量以检索和存储显示器的亮度信息，如下所示。

if (cameraData.isHDROutputActive && cameraData.postProcessEnabled)
{
    // Get luminance information from the display, these define the dynamic range of the display.
    float minNits = cameraData.hdrDisplayInformation.minToneMapLuminance;
    float maxNits = cameraData.hdrDisplayInformation.maxToneMapLuminance;
    float paperWhite = cameraData.hdrDisplayInformation.paperWhiteNits;
}
else
{
    // If HDR output is disabled, disable HDR output-related keywords
    // If post processing is disabled, the final pass will do the color conversion so there is
    // no need to account for HDR Output
    material.DisableKeyword(HDROutputUtils.ShaderKeywords.HDR_INPUT);
}

从 Volume Manager 中检索色调映射将图像的 HDR 值重新映射到适合在屏幕上显示的范围内的过程。更多信息
请参阅词汇表组件。

if (cameraData.isHDROutputActive && cameraData.postProcessEnabled)
{
    var tonemapping = VolumeManager.instance.stack.GetComponent<Tonemapping>();

    // Get luminance information from the display, these define the dynamic range of the display.
    float minNits = cameraData.hdrDisplayInformation.minToneMapLuminance;
    float maxNits = cameraData.hdrDisplayInformation.maxToneMapLuminance;
    float paperWhite = cameraData.hdrDisplayInformation.paperWhiteNits;
}

添加另一个 if 语句以检查是否存在色调映射组件。如果找到色调映射组件，则可以覆盖显示器的亮度数据。

if (cameraData.isHDROutputActive && cameraData.postProcessEnabled)
{
    var tonemapping = VolumeManager.instance.stack.GetComponent<Tonemapping>();

    // Get luminance information from the display, these define the dynamic range of the display.
    float minNits = cameraData.hdrDisplayInformation.minToneMapLuminance;
    float maxNits = cameraData.hdrDisplayInformation.maxToneMapLuminance;
    float paperWhite = cameraData.hdrDisplayInformation.paperWhiteNits;

    if (tonemapping != null)
    {
        // Tone mapping post process can override the luminance retrieved from the display
        if (!tonemapping.detectPaperWhite.value)
        {
            paperWhite = tonemapping.paperWhite.value;
        }
        if (!tonemapping.detectBrightnessLimits.value)
        {
            minNits = tonemapping.minNits.value;
            maxNits = tonemapping.maxNits.value;
        }
    }
}

使用显示器和色调映射的亮度数据设置材质的亮度属性。

if (cameraData.isHDROutputActive && cameraData.postProcessEnabled)
{
    var tonemapping = VolumeManager.instance.stack.GetComponent<Tonemapping>();

    // Get luminance information from the display, these define the dynamic range of the display.
    float minNits = cameraData.hdrDisplayInformation.minToneMapLuminance;
    float maxNits = cameraData.hdrDisplayInformation.maxToneMapLuminance;
    float paperWhite = cameraData.hdrDisplayInformation.paperWhiteNits;

    if (tonemapping != null)
    {
        // Tone mapping post process can override the luminance retrieved from the display
        if (!tonemapping.detectPaperWhite.value)
        {
            paperWhite = tonemapping.paperWhite.value;
        }
        if (!tonemapping.detectBrightnessLimits.value)
        {
            minNits = tonemapping.minNits.value;
            maxNits = tonemapping.maxNits.value;
        }
    }

    // Pass luminance data to the material, use these to interpret the range of values the
    // input will be in.
    material.SetFloat("_MinNits", minNits);
    material.SetFloat("_MaxNits", maxNits);
    material.SetFloat("_PaperWhite", paperWhite);
}

检索当前色彩空间的色域并将其传递给材质。

// Pass luminance data to the material, use these to interpret the range of values the
// input will be in.
material.SetFloat("_MinNits", minNits);
material.SetFloat("_MaxNits", maxNits);
material.SetFloat("_PaperWhite", paperWhite);

// Pass the color gamut data to the material (colorspace and transfer function).
HDROutputUtils.GetColorSpaceForGamut(cameraData.hdrDisplayColorGamut, out int colorspaceValue);
material.SetInteger("_HDRColorspace", colorspaceValue);

启用 HDR 输出着色器关键字。

// Pass the color gamut data to the material (colorspace and transfer function).
HDROutputUtils.GetColorSpaceForGamut(cameraData.hdrDisplayColorGamut, out int colorspaceValue);
material.SetInteger("_HDRColorspace", colorspaceValue);

// Enable HDR shader keywords
material.EnableKeyword(HDROutputUtils.ShaderKeywords.HDR_INPUT);

在您的 Execute() 函数中调用 SetupHDROutput 方法，以确保在使用此 Scriptable Render Pass 时始终考虑 HDR 输出。

完整脚本示例

以下是示例中的完整代码。

class CustomFullScreenRenderPass : ScriptableRenderPass
{
    // Leave your existing Render Pass code here

    static void SetupHDROutput(ref CameraData cameraData, Material material)
    {
        // If post processing is enabled, color grading has already applied tone mapping
        // As a result the input here will be in the display colorspace (Rec2020, P3, etc) and in nits
        if (cameraData.isHDROutputActive && cameraData.postProcessEnabled)
        {
            var tonemapping = VolumeManager.instance.stack.GetComponent<Tonemapping>();

            // Get luminance information from the display, these define the dynamic range of the display.
            float minNits = cameraData.hdrDisplayInformation.minToneMapLuminance;
            float maxNits = cameraData.hdrDisplayInformation.maxToneMapLuminance;
            float paperWhite = cameraData.hdrDisplayInformation.paperWhiteNits;

            if (tonemapping != null)
            {
                // Tone mapping post process can override the luminance retrieved from the display
                if (!tonemapping.detectPaperWhite.value)
                {
                    paperWhite = tonemapping.paperWhite.value;
                }
                if (!tonemapping.detectBrightnessLimits.value)
                {
                    minNits = tonemapping.minNits.value;
                    maxNits = tonemapping.maxNits.value;
                }
            }

            // Pass luminance data to the material, use these to interpret the range of values the
            // input will be in.
            material.SetFloat("_MinNits", minNits);
            material.SetFloat("_MaxNits", maxNits);
            material.SetFloat("_PaperWhite", paperWhite);

            // Pass the color gamut data to the material (colorspace and transfer function).
            HDROutputUtils.GetColorSpaceForGamut(cameraData.hdrDisplayColorGamut, out int colorspaceValue);
            material.SetInteger("_HDRColorspace", colorspaceValue);

            // Enable HDR shader keywords
            material.EnableKeyword(HDROutputUtils.ShaderKeywords.HDR_INPUT);
        }
        else
        {
            // If HDR output is disabled, disable HDR output-related keywords
            // If post processing is disabled, the final pass will do the color conversion so there is
            // no need to account for HDR Output
            material.DisableKeyword(HDROutputUtils.ShaderKeywords.HDR_INPUT);
        }
    }
}

在 URP 中实现兼容 HDR 输出的自定义叠加

图形性能和分析

Unity 手册

URP 中使用 HDR 输出的 Scriptable Render Pass 疑难解答

在脚本中进行色调映射和色彩空间转换

完整脚本示例